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Demonstration of platelet activating factor receptor in guinea pig kidney
T Takano1, Z Honda, T Watanabe
1First Department of Internal Medicine, University of Tokyo, Japan.
Abstract:
Distribution of platelet activating factor (PAF) receptor was examined in the guinea pig kidney. Northern blot analysis showed a single band electrophoresed just below the 28S rRNA, and the mRNA was richest in the cortex with lesser amounts in the outer and then inner medulla. Scatchard analysis of membrane fraction using [3H]WEB 2086, a specific PAF receptor antagonist, revealed a single binding site with Bmax of 522, 228, 58 fmol/mg protein for the cortex, outer medulla and inner medulla, respectively. Kd values were in the same order of magnitude (10(-8) M). These results indicate the presence of a single class of PAF receptor in the guinea pig kidney which is most abundant in the cortex.
Insights
Platelet activating factor (PAF) receptors are present in guinea pig kidneys, with the highest concentration found in the renal cortex. This study mapped the distribution of these important PAF receptors.
Area of Science:
- Nephrology
- Pharmacology
- Molecular Biology
Background:
- Platelet-activating factor (PAF) is a potent lipid mediator involved in various physiological and pathological processes.
- Understanding the distribution of PAF receptors is crucial for elucidating its role in kidney function and disease.
Purpose of the Study:
- To investigate the localization and quantification of platelet activating factor (PAF) receptors in the guinea pig kidney.
- To determine the relative abundance of PAF receptors in different kidney regions: cortex, outer medulla, and inner medulla.
Main Methods:
- Northern blot analysis was employed to detect and analyze the messenger RNA (mRNA) for the PAF receptor.
- Scatchard analysis using a specific radiolabeled PAF receptor antagonist ([3H]WEB 2086) was performed on kidney membrane fractions.
Main Results:
- Northern blot analysis revealed a single PAF receptor mRNA transcript, predominantly expressed in the renal cortex.
- Scatchard analysis identified a single class of PAF binding sites across kidney regions.
- The maximum binding capacity (Bmax) for PAF receptors was highest in the cortex (522 fmol/mg protein), followed by the outer medulla (228 fmol/mg protein) and inner medulla (58 fmol/mg protein).
- Dissociation constants (Kd) were in the 10(-8) M range, indicating high-affinity binding.
Conclusions:
- The guinea pig kidney expresses a single class of platelet activating factor (PAF) receptor.
- PAF receptors are most abundantly distributed in the renal cortex compared to the medullary regions.
- These findings provide a basis for further research into the specific roles of PAF in renal physiology and pathophysiology.